SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c50328caba271442f3ea56b122f45f822aba0fe24ed0682c95dd60693ccbd32a' 
  AND token = 'zAFN9uNd8ltKK/1BcMOachzF75tr6AJs7IH709PHEy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}